Zitat:
If a USB Storage Device Is Not Already Installed on the Computer
If a USB storage device is not already installed on the computer, assign the user or the group Deny permissions to the following files:
• %SystemRoot%\Inf\Usbstor.pnf
• %SystemRoot%\Inf\Usbstor.inf
When you do so, users cannot install a USB storage device on the computer. To assign a user or group Deny permissions to the Usbstor.pnf and Usbstor.inf files, follow these steps:
1. Start Windows Explorer, and then locate the %SystemRoot%\Inf folder.
2. Right-click the Usbstor.pnf file, and then click Properties.
3. Click the Security tab.
4. In the Group or user names list, click the user or group that you want to set Deny permissions for.
5. In the Permissions for UserName or GroupName list, click to select the Deny check box next to Full Control, and then click OK.
Note In addition, add the System account to the Deny list.
6. Right-click the Usbstor.inf file, and then click Properties.
7. Click the Security tab.
8. In the Group or user names list, click the user or group that you want to set Deny permissions for.
9. In the Permissions for UserName or GroupName list, click to select the Deny check box next to Full Control, and then click OK.
If a USB Storage Device Is Already Installed on the Computer
Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
322756 (http://support.microsoft.com/kb/322756/) How to back up and restore the registry in Windows

If a USB storage device is already installed on the computer, set the Start value in the following registry key to 4:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\UsbStor
When you do so, the USB storage device does not work when the user connects the device to the computer. To set the Start value, follow these steps:
1. Click Start, and then click Run.
2. In the Open box, type regedit, and then click OK.
3. Locate, and then click the following registry key:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\UsbStor
4. In the right pane, double-click Start.
5. In the Value data box, type 4, click Hexadecimal (if it is not already selected), and then click OK.
6. Quit Registry Editor.